Thermoelectric properties of n-doped Mg2Si

Heat from different sources can be converted into electricity by thermoelectric materials. In order to widen thermoelectric energy conversion for large scale current generation or waste heat recovery application, Mg2Si and related alloys are appealing candidates as thermoelectric materials in the middle-high temperature range[1]. They are characterized by low toxicity, high abundance of the constituent elements and low densities compared to PbTe or CoSb3 used in the same temperature range (500-850K) [2]. The efficiency of a TE material is related to its figure of merit ZT=?2T/(??) where ? is the Seebeck coefficient, ? the electrical resistivity and ? the thermal conductivity. The thermoelectric performance can be improved by doping of the Mg2Si matrix with heavier elements such as Bi or Sb. This results in higher electrical conductivity and lower thermal conductivity. In this work, Bi- and Sb -doped Mg2Si are obtained by solid state synthesis starting from commercial raw Mg2Si or element melting. The powders are consolidated into dense pellets (95% of bulk density) by spark plasma sintering. The thermal and electrical conductivity and the Seebeck coefficient are evaluated in the temperature range RT-600°C. The influence of the synthesis conditions is discussed in term of thermoelectric properties of materials.